What we can find in what’s left behind: DNA metabarcoding of amphibiotic insect exuviae

Abstract

The phenomenon of insect emergence represents a transfer of mass and energy from aquatic to terrestrial systems and is a critical part of ecosystem connectivity and functioning. Traditional methods of studying insect emergence rely on the capture of insects as they emerge and on morphological identification with taxonomic keys. This can be both time consuming and impact study populations, obstacles that can be removed with DNA obtained from biological remnants. The present proof-of-concept study investigated the potential of using exuviae collected from the water surface as a DNA source. Emergence trap samples and insect exuviae were collected from a pond and a small creek. Sample types were generally not statistically distinguishable, but the exuviae samples identified more orders containing amphibiotic insects and a higher level of diversity within these orders than the trap samples did. This higher level of diversity seen in exuviae samples may be due to limitations of emergence traps, including that they alter environmental variables in their collection area. We demonstrated that identification of emerging aquatic insects through metabarcoding of exuviae is a useful method for the study of insect emergence and could be used for biodiversity assessments and studies on emergence times and to better understand ecosystem connectivity.